序言

还是参考的菜鸟教程，会C++的还是看C++的方式来得舒服。

理解

使用符合UML规范的便于理解和回忆，接口其实就是普通的基类
策略模式
.

源码

strategy.h

/// 策略
class Strategy
{
public:virtual ~Strategy();/*** @brief 计算* @param num1 计算数值* @param num2 被计算数值* @return */virtual int operation(const int& num1, const int& num2) = 0;
};/// 加策略
class AddOperation : public Strategy
{
public:/*** @brief 加计算* @param num1 计算数值* @param num2 被计算数值* @return */int operation(const int &num1, const int &num2) override;
};/// 减策略
class SubtractOperation : public Strategy
{
public:/*** @brief 减计算* @param num1 计算数值* @param num2 被计算数值* @return */int operation(const int &num1, const int &num2) override;
};/// 上下文
class Context
{
public:/*** @brief 构造一个策略的上下文* @param strategy 策略对象*/explicit Context(Strategy *strategy);~Context();/*** @brief 计算* @param num1 计算数值* @param num2 被计算数值* @return */int operation(const int &num1, const int &num2);private:/// 所拥有的策略Strategy *strategy = nullptr;
};

.
strategy.cpp

Strategy::~Strategy()
{}int AddOperation::operation(const int &num1, const int &num2)
{return num1 + num2;
}int SubtractOperation::operation(const int &num1, const int &num2)
{return num1 - num2;
}Context::Context(Strategy *strategy): strategy(strategy)
{}Context::~Context()
{if (strategy)delete strategy;
}int Context::operation(const int &num1, const int &num2)
{if (strategy){return strategy->operation(num1, num2);}return INT_MIN;
}

.
使用的地方

std::shared_ptr< Context > context(new Context(new AddOperation));
std::cout << context->operation(10, 5) << std::endl;context.reset(new Context(new SubtractOperation));
std::cout << context->operation(10, 5) << std::endl;